(19)
(11) EP 0 616 234 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
25.01.1995 Bulletin 1995/04

(43) Date of publication A2:
21.09.1994 Bulletin 1994/38

(21) Application number: 94104327.5

(22) Date of filing: 18.03.1994
(51) International Patent Classification (IPC)5: G02B 6/12, G02B 1/04, C08G 73/00
(84) Designated Contracting States:
DE FR GB NL

(30) Priority: 18.03.1993 JP 82516/93
28.06.1993 JP 178574/93

(71) Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Shinjuku-ku, Tokyo 163-19 (JP)

(72) Inventors:
  • Maruo, Yasuko
    Kodaira-shi, Tokyo (JP)
  • Sasaki, Shigekuni
    Iruma-shi, Saitama-ken (JP)
  • Tamamura, Toshiaki
    Atsugi-shi, Kanagawa-ken (JP)
  • Matsuura, Tohru
    Yokohama-shi (JP)
  • Ando, Shinji
    Tokyo (JP)
  • Matsui, Shinsuke
    Kodaira-shi, Tokyo (JP)
  • Yamamoto, Fumio
    Hoya-shi, Tokyo (JP)

(74) Representative: Schmidt-Evers, Jürgen, Dipl.-Ing. et al
Patentanwälte Mitscherlich & Partner, Sonnenstrasse 33
80331 München
80331 München (DE)


(56) References cited: : 
   
       


    (54) Polyimide optical waveguide and method of manufacturing the same


    (57) A polyimide optical waveguide comprising a core (2) made of polyimide whose refractive index is controlled to a predetermined value by electron beam irradiation, and a cladding (1, 3) set in contact with the core and having a refractive index lower than that of the core.
    A polyamic acid solution is spin-coated on a substrate such as of silicon, and is thermally cured to form a polyimide layer. An electron beam is irradiated on the entire surface of the polyimide layer to change the refractive index to a predetermined value. An electron beam-absorbed dose of the polyimide layer depends on the composition of the polyimide, an energy of the electron beam, and the applied amount of the electron beam irradiation. The refractive index changes in accordance therewith approximately.
    This polyimide layer irradiated with the electron beam is used as a core layer.
    Next, the same polyamic acid solution is spin-coated on the core layer, and is thermally cured. The material is separated from the substrate to obtain a polyimide film of a two-layer structure.
    Then, the polyimide film of a two-layer structure is made to reverse and the irradiated polyimide layer is made to the upper surface. The lower surface of the reversed film is adhered by a method such as a thermo-compression bonding on the other silicon substrate.
    Next, the core layer is patterned into a desired shape, for example, a rectangular shape, by RIE (reactive ion etching) method.
    Finally, the same polyamic acid solution is spin-coated over the patterned core layer, as an upper cladding lacer, and is thermally cured, thereby preparing an embedded channel waveguide.






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